Patent GB-236318-A (GB)
Title: Means for controlling electric circuits at predetermined times
IPC: G04C23/34
Filed: 1924-04-23
Abstract: 236,318. Woronam, A., (Ederer, L.). April 23, 1924. Time alarms.-A machine for closing alarm or other circuits at predetermined times according to the programme is operated by impulses from a master clock which actuates a series of switches corresponding to minutes, hours, and days of the week. The times during the week at which the circuits are to be closed are selected by inserting plugs in cross-bar commutators. General arrangement. In the example shown, two different programmes can be arranged by inserting plugs in the commutators S, S<1>. one being applicable to Saturdays and Sundays, the other to the remaining week-days. With each commutator is associated (1) a minute switch X or X<1> comprising sixty contacts arranged in two semi-circles one below the other, and a wiper C<2> for the minutes from 1 to 30, and a second wiper C<12> (making 180‹ with the first) for the minutes from 31 to 60. the two pairs of wipers being mounted on a single shaft along with a control wiper F' and stepped round under the control of the master clock E; and (2) an hour switch T or T<1>, the wipers K<9>, M<1> of which are stopped round under the control of the minutes wiper F<3>, and are mounted on a single shaft with a control wiper G<5>. The commutators S. S<1> are connected to different groups of contacts on the day-of-the-week switch V, the wiper B' of which is stepped round under the control of the hours wiper G<5>. An alarm or other circuit W or W<1> is closed whenever a circuit is completed through the armature K of the control magnet E<2>, minutes switch X or X<1>, commutator S or S<1>, hour switch T or T<1>, and day-ofthe-week switch V. The programme can be annulled as described below on public holidays. Step-by-step driving of switches. The machine is driven from the control magnet E<2>, which receives an impulse every minute from the master clock E and through its armature E<4> energizes the motor-magnet C<8> which steps round by pawl- and-ratchet action the shaft carrying the wipers C<2>, C<12>, F<3> of the minutes switch, and at the same time closes contact at F. The latter action normally produces no effect, but when the wiper F' reaches the contact 59<1> one minute before the completion of an hour, a circuit is closed through F<4>, F<3>, F, earth, battery B<14>, and hour-magnet B<12>, so as to move the hour shaft carrying the wipers K<9>, M<1>, G<5> one step forward. For convenience in manufacture there are 25 contacts arranged in a semicircle for each hours wiper, and each such wiper has two parts set at 180‹ so that one part is always in operation. It is therefore necessary to move the hour shaft two steps at the end of the twenty-fifth hour, and to this end the contact 25<1> is connected through a magnet G<1> to the contact 60<1> so that this magnet is energized at the sixtieth minute of the twenty-fifth hour, its armature G<16> effecting the energization of the hours-motor-magnet B<12> for the second time that hour. In order that the wiper G<5> may be relieved of current a hold-on circuit is closed through the make-before-break contact G<18>. The day-of-the-week switch V is operated once a day when the wiper G<5> reaches the contact a energizing the relay H<1>. which immediately relieves the wiper G<5> of current and substitutes a holdon circuit through the make-before-break contact H<4>. The relay H<1> at the same time closes at H<5> the circuit of the motor magnet H<11> which moves the wiper B' of the day-of-the-week switch V one step forward by pawl-and-ratchet mechanism acting against a spring. and when the wiper reaches its eighth contact B' it is returned to its starting point B<1> by the spring. To this end the contact B<8> is connected to a delay-action relay J<4> which closes the circuit of a magnet J<9> which releases the holding pawl H<15> that normally prevents the wiper B<9> from being restored to the contact B<1>. and owing to the delay action of the relay J<4> the holding pawl is not released until the driving pawl of the motormagnet H<11> has moved clear of the ratchet. Annulling device for holidays. In a modification the switch V is so constructed that the device can be put out of action for any desired day of the week.